Metallic heat exchanger tube

Abstract

A metallic heat exchanger tube (1) with a tube wall (2) and with integrally formed ribs (3) which run around on the tube outside (21) and which have a rib foot (31), rib flanks (32) and a rib tip (33), the rib foot (31) projecting essentially radially from the tube wall (2), and the rib flanks (32) being provided with additional structural elements which are formed as material projections (4) arranged laterally on the rib flank (32), the material projections (4) having a plurality of boundary faces (41, 42), at least one of the boundary faces (42) of at least one material projection (4) being curved convexly.

The invention claimed is: 
     
       1. A metallic heat exchanger tube ( 1 ) for a vapour with a tube wall and with integrally formed ribs which run around on the tube outside and have a rib foot, rib flanks and a rib tip, the rib foot projecting essentially radially from the tube wall, and the rib flanks being provided with additional structural elements which are formed as material projections which are arranged laterally on the rib flank, the material projections having a plurality of boundary faces, characterized in that at least one of the boundary faces of at least one material projection is curved convexly and the local radius of curvature of the convex boundry face is reduced with an increasing distance from the rib flank. 
     
     
       2. The metallic heat exchanger tube according to  claim 1 , characterized in that the convexly curved boundary face is a boundary face of a material projection which faces away from the tube wall. 
     
     
       3. The metallic heat exchanger tube according to  claim 1 , characterized in that the curvature of the boundary face is also curved convexly in a plane parallel to the rib flank, the curvature of the convex boundary face in a plane perpendicular to the rib flank being greater than the curvature of the convex boundary face in the plane parallel to the rib flank. 
     
     
       4. The metallic heat exchanger tube according to  claim 1 , characterized in that the radius (RM) of an imaginary circle (K), which lies in a sectional plane perpendicular to the tube circumferential direction (U) and is defined by the points P 1 , P 2  and P 3 , is smaller than 1 mm, P 1  being the point at which the convex boundary face of the material projection is contiguous to the rib flank, P 3  being the point at which the convex boundary face of the material projection is furthest away from the rib flank, and P 2  being the center point between P 1  and P 3  on the contour line of the convex boundary face of the material projection. 
     
     
       5. The metallic heat exchanger tube ( 1 ) according to  claim 4 , characterized in that the convex boundary face of the material projection, in the region of the tip (SP) of the latter, is continued with the convex curvature beyond the point P 3  furthest away from the rib flank. 
     
     
       6. The metallic heat exchanger tube ( 1 ) according to  claim 1 , characterized in that the material projections arranged on the rib flank are spaced apart in the circumferential direction (U). 
     
     
       7. The metallic heat exchanger tube ( 1 ) according to  claim 1 , characterized in that the material projections arranged on the rib flank are spaced apart equidistantly and at least by the amount of their width in the circumferential direction (U).